This disclosure relates to heating a reaction chamber, for example, a reaction chamber for oxidizing fuel in a gas turbine system. Some conventional reaction chambers (e.g., thermal oxidizers) are initially heated by using an ignition source to ignite highly-concentrated rich fuels (e.g., highly-concentrated natural gas) in the reaction chamber. In such conventional reaction chambers, after the highly-concentrated rich fuels heat the reaction chamber to a high temperature, low-BTU gas may be destroyed in the hot reaction chamber by oxidizing the low-BTU gas at a high temperature.